Insights into adopted synthetic approaches for 1,2,4-oxadiazoles: A review

A five-membered heterocyclic compound known as 1,2,4-oxadiazole has one oxygen, two carbon, and two nitrogen atoms within a ring. Numerous studies have shown that 1,2,4-oxadiazole has the potential as a useful pharmacophore in many harmful pharmacological conditions such as microbiocidal, anti-inflammatory, anti-tuberculosis, Meibomian gland dysfunction, etc. In this present review, we highlighted the synthetic protocols (based on the starting substrate) for 1,2,4-oxadiazoles which have been adopted in the last nine years (2015 to 2023). The study also involved a listing of several patents (granted) which comprised important work on 1,2,4-oxadiazole and its derivatives. Among all the methods, the most commonly adopted synthetic methods included the synthesis of 1,2,4-oxadiazoles from amidoxime, nitriles, chloroximes, benzaldehyde, vinyl benzene, benzamides, etc. These synthetic protocols have also been compared based on different reaction conditions, feasibility, and economy to help the researchers in designing their work.